Brake, especially for wind farms

ABSTRACT

Brake, in particular for wind power plants, including a set of brake shoes ( 16, 18 ) and an actuator ( 28 ) for the brake shoes, in which the actuator ( 28 ) acts upon a lever ( 24 ) which is pivotable in a plane in parallel with the brake shoes ( 16, 18 ) and acts upon the brake shoes ( 16, 18 ) through a transmission ( 22 ) which translates the pivotal movement into an axial movement.

The invention relates to a brake, in particular for wind power plants,comprising a set of brake shoes and an actuator for the break shoes.

Brakes for the rotor of a wind power plant or similar large equipmentmust be capable of producing a high braking force and therefore requirea sufficiently strong actuator. Heretofore, a hydraulic actuator hasbeen used which directly generates the engaging force for the brakeshoes. The relatively large and heavy piston and cylinder unit of thehydraulic actuator is then arranged immediately behind the brake shoes.In a spacially restricted environment as for example in the engine podof a wind power plant, it may therefore be difficult to providesufficient space for the actuator.

Hydraulic actuators have the further disadvantage that they arerelatively harmful to the environment, are expensive and require a highmaintenance effort, because a suitable hydraulic fluid as well as sealsand the like for sealing the hydraulic system are needed and because,for reasons of operational safety, the fill state of the hydraulic fluidmust be checked from time to time. Under these aspects, it would bedesirable to employ an electromechanical actuator in place of ahydraulic actuator. However, it turns out to be difficult to provide asufficient engaging force for the brake shoes by means of anelectromechanical actuator.

It is an object of the invention to provide a brake of the typeindicated above, which permits more design freedom in terms of theconstruction and arrangement of the actuator.

This object is achieved by the feature that the actuator acts upon alever which is pivotable in a plane in parallel with the brake shoes andacts upon the brake shoes via a transmission which translates thepivotal movement into an axial movement.

Thus, in the brake according to the invention, the actuator can bearranged laterally offset from the brake shoes, which turns out to theadvantages under certain installation conditions. Since, moreover, theactuator acts upon the brake shoes via the lever and via thetransmission, it is possible to substantially boost the actuating forceby means of the leverage effect and the effect of the transmission, sothat, accordingly, the actuator itself may be designed to be weaker. Inparticular, this makes it possible also to employ an electromechanicalactuator.

Advantageous details of the invention are indicated in the dependedclaims.

The transmission is preferably formed by a spindle which is heldnon-rotatably and axially displaceably in a housing and carries one ofthe brake shoes at one of its ends and is in engagement with a threadedsleeve at the radially inner end of the lever.

For reducing the actuating resistance, the threaded sleeve may be formedby a ball lining. It is also possible to employ a planet rollerthreading, a planet roller-type threaded spindle or a differentialroller spindle. It is further preferable to support the threaded sleevein the housing by means of roller bearings and, in particular, tosupport it against the actual reaction forces that are produced when thespindle is operated, by means of an axial bearing.

The brake may optionally be designed as an active brake in which thebrake shoes are brought in the braking position when the actuator isenergised, or as a passive brake, such as a spring accumulator brake, inwhich the actuator must be energised in order to retain the brake in thenon-braking position, so that the brake will automatically becomeactive, when the power of the actuator is cut off. In the latter case,the spindle must be displaced by means of the transmission and the leverin a direction opposite to the brake shoes in order to bias the springassembly. In a particularly preferred embodiment, the transmission is sodesigned that it my be mounted in the housing in reverse positions,depending on the application case, so that active and passive brakes maybe constructed with the use of mostly identical components, and a simpleconversion from one brake type to the other is possible.

Embodiment examples of the invention will now be explained inconjunction with the drawings in which:

FIG. 1 is a view of a disk brake for a wind power plant;

FIG. 2 is a sectional view taken along the line II - II in FIG. 1; and

FIG. 3 is a sectional view of a spring accumulator brake.

The disk brake shown in FIGS. 1 and 2 has a floating calliper 12 whichis arranged at the rim of a brake disk 10 and is slideably guided onguide bars 14 extending in parallel with the axis of the brake disk 10,and which straddles the brake disk with two brake shoes 16, 18, as isshown in FIG. 2. Mounted to the floating calliper 12 is a housing 20which accommodates a transmission 22, with a lever 24 projecting out ofthe housing, said lever being pivotable about the axis of thetransmission 22 in a plane that is parallel to the brake disk 10 and thebrake shoes 16, 18.

The free end of the lever 24 is articulated to an actuator rod 26 of anelectromechanical actuator 28. In the example shown, the actuator 28 isarticulated to a support 30, that is secured to a frame of the windpower plant. As an alternative, the actuator 28 might also be secured tothe calliper 12 by means of a bracket 32, as is shown in phantom linesin FIG. 1.

In the example shown, the transmission 22 is formed by a spindle 34which carries, in its central portion, a threading 36, e. g. a ballthreading, and is engagement with a threaded sleeve 38, e. g. a balllining that is arranged at the inner end of the lever 24. The endportions of the spindle 34 situated on either side of the threading 36are slideably guided in slide bearings 40, 42 and have keys 44 withwhich the spindle is secured against rotation. The threaded sleeve 38 isrotatably supported in the housing 20 by means of radial roller bearings46. On a side facing away from the brake shoes 16, 18, it isadditionally supported in the transmission housing by an axial bearing48.

The end of the spindle 34 shown on the left side in FIG. 1 is connectedto the movable brake shoe 18. When, by means of the actuator 28, thelever 24 is pivoted about the axis of the spindle 34, the spindle 34 isdisplaced towards the left in FIG. 2, and the brake shoes 16, 18 areevenly pressed against the brake disk. The reaction forces which thenact upon the threaded sleeve 38 are absorbed by the axial bearing 48.

In the example shown, the actuator 28 is reversible, and the brake isdisengaged by extending the actuator rod 26 by means of the actuator, sothat the lever 24 is returned to the original position.

FIG. 3 shows a modified embodiment of the brake which, in this case, isconfigured as a spring accumulator brake. A spring accumulator 50 havinga spring assembly 52 is mounted to the side of the transmission housing20 facing away from the calliper 12. Here, the transmission 22 ismounted in the housing 20 in an inverted position, so that the axialbearing 48 is disposed on the side facing the brake shoes 16, 18. Theactuator, which has not been shown in FIG. 3, is energised when thebrake is inactive, and retains the spindle 34 in a position shiftedtowards the right, in which position it engages the spring assembly 52with a shifter 54 and holds it in the compressed state. When theactuator 28 is switched off (or is de-energised in case of powerblackout), the movable brake shoe 18 is shifted towards the right intothe breaking position by the compressed spring assembly 52 and via theshifter 54 and the spindle 34. In this case, the transmission 22 mustnot be self-locking, in order for the lever 24 to be pivotable by theforce of the spring assembly 52 alone.

In both embodiments, an additional catch or locking system may beprovided for the lever 24 and/or the actuator 28, so that the brake maybe locked in the active or inactive position or in both positions, evenwhen the actuator is not energised permanently.

Further, is may be useful that the lever 24 is made elastic or iselastically coupled to the threaded sleeve 38, e. g. by means of aoverrunning spring, so that the action of the actuator is dampenedand/or a reliable engagement of the locking system in the lockingposition is assured.

1. Brake, for wind power plants, comprising: a set of brake shoes, alever which is pivotable in a plane in parallel with the brake shoes, atransmission which acts upon the brake shoes and which translates thepivotal movement of the lever into an axial movement, and an actuatorfor causing the lever to pivot in said plane.
 2. Brake according toclaim 1, wherein the transmission is a spindle-type transmission. 3.Brake according to claim 2, wherein the transmission is a ball-typespindle transmission.
 4. Brake according to claim 2, wherein thetransmission has a spindle with a planetary ball threading.
 5. Brakeaccording to claim 2, wherein: the lever includes a threaded sleeve, andthe transmission comprises a spindle which is non-rotatably and axiallydisplaceably guided in a housing, has one end acting upon one of thebrake shoes and is in threaded engagement with the threaded sleeve. 6.Brake according to claim 5, wherein the threaded sleeve is supported inthe housing with ball bearings.
 7. Brake according to claim 5, whereinthe threaded sleeve has at least one axial end supported at the housingvia an axial bearing.
 8. Brake according to claim 1, wherein the brakeis configured as a spring accumulator brake, and further comprising aspring assembly for biasing the transmission to act upon the brakeshoes, and wherein the transmission biases the spring assembly when theactuator is active, and permits a force of the spring assembly to actupon the brake shoes when the lever is released.
 9. Brake accordingclaim 1, wherein the transmission is adapted to be mounted in a housingin an inverted position.